This is one of the most capable and expressive formats of all the file
formats supported by GPSBabel. It is described at topografix.com and is
supported by EasyGPS, ExpertGPS, and many other programs described at
topografix.com

GPSBabel's reader of this module attempts to preserve tags it doesn't
really understand. It also tries to glean interesting data from

snlen option

Length of generated shortnames.

When used with the -s to control shortnames, the snlen suboption to GPX controls how long the generated smartname will be. This can be useful for cases like writing GPX files to a GPS that has a fixed waypoint name length.

suppresswhite option

No whitespace in generated shortnames.

When used with the -s to generate smart shortnames, this suboption controls whether whitespace is allowed in the generated shortnames.

logpoint option

A typical use for this is to get coordinates read from "corrected coordinates" logs.

urlbase option

Base URL for link tag in output.

This is a fairly esoteric option. If the GPX file you are reading has only base pathnames (e.g "foo.html") the value you specify to this argument will be prepended to that. For example, "-o gpx,urlbase=c:\My Documents\Whatever" would result in the link to that waypoint being written to refer to c:\My Document\WHatever\foo.html

gpxver option

Target GPX version for output.

This option specifies the version of the GPX specification to use for
output. The default version is 1.0. The only other valid value for this
option is 1.1.

Notice that this is not a full scale XML schema conversion. In particular,
if you have a GPX 1.0 file that has extended namespaces in it (such as a
pocket query from Geocaching.com) just writing it with this option will
result in a horribly mangled GPX file as we can't convert the schema data.